Mineral white oil treatment



MINERAL WHITE OIL TREATMENT No Drawing. Application July 13, 1956 Serial No. 597,589

4 Claims. (Cl. 208-274) This invention relates to an improvement of washing color-forming impurities from. a mineral-acid-treated white oil by using certain organic solvents added to aqueous isopropanol as the washing solvent.

The kind of organic solvents now found advantageous for addition to aqueous propanol to accomplish the objects set forth are characterized by: boiling points close to that of isopropyl alcohol, i.e. 56.5 to 97 C., a solvency in 50% aqueous isopropanol at 25 C. of 5 to 30 vol. percent, and low solubility for C paraifinic hydrocarbons, less than 3% by volume.

Solvents that are advantageous are listed below:

B.P., C. Acetone 56.5 Ethyl alcohol 78.4 Methyl ethyl ketone 79.6 Tert. butyl alcohol 82.9 Ethyl acetate 80 Sec. butyl alcohol 95 Methyl n-propyl ketone 97 soluble organic solvent added to an aqueous isop-ropanol containing 50 vol. percent isopropanol, or in the range of 40 to 60 vol. percent isopropanol.

The wash solvent can be used in about equal parts by volume with respect to the white oil or thereabouts depending on the degree of purification desired. The

washing temperatures are generally in the range of 20 to 100 0., preferably 50 to 80 C.

The production of technical and white mineral oils from high boiling petroleum fractions requires large quantities of oleum in successive treats. A complex mixture of sulfona-tion products are formed, including sulfonic acids, highly colored asphaltic and resinous compounds and other deleterious impurities. Most of these sulfonation products collect in an oil insoluble tarry acidsludge which separates out after treatment, but some colored impurities remain in the acid oil layer along with the high molecular weight sulfonic acids. The complete removal of the color bodies from the oil layer is highly advantageous as these materials further react with the 2,900,333 Patented Aug. 18, 1.959

successive oleum treats and also impart color to the finished neutral oil.

A typical white oil treating method is summarized:

(1) A 10 vol. percent oleum treat at C. followed by settling and separation of the acid oil from the sludge formed.

(2) An 8 vol. percent oleum treat as in (1).

(3) Neutralization of the intermediate acid oil with aqueous sodium carbonate and two washes of volume percent of fifty percent aqueous isopropanol at 70 C. to recover the sulfonates.

(4) Steaming of the Washed intermediate neutral oil at C. to remove traces of isopropanol and water.

(5) Three successive treats of 5 vol. percent oleum at 40 C. as in (1).

(6) Neutralization and Washing of the final acid oil as in (3).

(7) Steaming as in (4).

(8) Percolation of the finished neutral oil through 5 Wt./vol. percent of 30/60 mesh roasted attapulgus clay to produce a finished white oil.

The usual expression of this typical method is as follows:

Treat-Treat-Wash'lreat-Treat-Treat-Wash 1 2 3 & 4 5 5 5 s & 7

A 50% aqueous isopropanol Wash is used in steps 3 and 6 to remove the sulfonates from the neutralized acid oil. This solvent does not remove the deleterious color bodies from the oil completely. To overcome this deficiency, about 5 to 30 vol. percent of a selected solvent is added to the isopropanol wash to increase its solvent power in removing all the color bodies from the oil.

Color bodies not removed from the intermediate and final neutral oils after washing are further degraded and darkened by the steaming operating at 125 C. This places an additional burden on the efficiency of the final oleum treating and on the clay percolation of the finished neutral oil.

Advantages of the improved process method:

(1) More efficient utilization of the oleum.

(2) Improved clay filter yields of finished white oil.

(3) Improved quality technical oils can be produced. (4) Finished white oil'of higher quality can be produced.

EXAMPLE 1 Sixteen'hundred ml. of acid oil having a Saybolt universal viscosity of 360 seconds at 100 F. from an acid agitation settler overflow, plant production, was separated into two 800 ml. portions. One portion was neutralized with aqueous sodium carbonate and given one Wash of 800 ml. of 50% aqueous isopropanol at 70 C. The other portion was neutralized with aqueous sodium carbonate and given one Wash of 800 m1. of 50% aqueous isopropanol containing 25 vol. percent of methyl ethyl ketone (M.E.K.). Both samples were settled hot, the alcoholic sulfonate layer drawn off, the oil layer steamed at 125 C. for /2 hour, cooled, then percolated through vS-wt. percent of 30/60 mesh attapulgus clay per column of oil. Methyl ethyl ketone is found to be a most suitable solvent to use in combination with isopropyl alcohol since'it has an excellent solubilizing effect on color bodies not removed by the alcohol. These color bodies appear to b'e-most readily extracted by solvents containing Oxo or carbonyl functions.

The neutral and the percolated white oils have the following characteristics:

Inspections Isopropanol IsopropanoLMEK Spec, Washed Sample Washed Sample Acid Oil 800 ml. Overflow Pep- 800 ml. Overflow Pepper s/ludgo content syludge content= Neutralizer Solvent Wash Aqueous NSHCOQ 800 Aqueous NazCOa 800 at 70 C. mlfof 50% Aqueous ml. of 50% aqueous Isopropanol. Isopropanol contain- W A 7 ing 25 Vol. Percent M.E.K. Neutral Oil Color 2 Sayholt +17 Saybolt Finished Percolated White 7 Oil wt. percent Clay):

Optical Density 0.37 5 0.185 .2 max. Color, Sayb 0 +30 on +30 min. U.S.P. Carbonizable 1.53 0.87 3max.

Substance.

' EXAMPLE 2 In normal production, it requires at least two 100 vol.

Acid oil overflow from an acid treater settler containing 0.6% pepper sludge, was used in this study. Volumes of 800 m1. of acid oil, 600 ml. of 50% aqueous isopropa- 1101, and 200 ml. of .solvent were mixed together at 25 C. Then 70 ml. of saturated aqueous Na CO was added to neutralize the acid oil, the mixture heated to 55 C. in minutes and settled hot. The alcoholic soap layer was drawn off, the oil layer brightened by settling at 60 C. on a steam bath after which the oil was steamed /2 hour at 125 C. The neutral oil was cooled, paper filtered to remove any moisture, and precolated through 5 wt. percent of 30-60 mesh roasted Attapulgus clay per volume of oil. The finished white oil was inspected for color, optical density, and U.S.P. carbonizable substances. See the following table.

At a concentration of 25 vol. percent of selected solvent in a 100 vol. percent wash per volume of acid oil, none of the solvents examined showed an incompatibility to the 50% aqueous alcohol or to the saturated aqueous sodium carbonate solution used in neutralization. The volume ratio of this improved wash is 2.5 parts solvent to 3.75 parts 100% isopropanol to 3.75 parts of water; which is the right strength for each component to be most effective in the neutralizing and extracting from the acid oil the sulfonate and color bodies.

percent alcohol washes to remove all the sulfonate and color bodies from the neutral oil. The new treating procedure of the present invention achieves the same effect with only one wash. The color and stability inspections on the oils clearly show the added quality of the alcoholwashed product over the conventional alcohol washed oil.

The invention described is claimed as follows:

1. In a process for washing a white oil formed by sulfuric acid treatment following neutralization of the treated oil to remove color-forming organic impurities from said oil, the improvement which comprises washing said oil with about equal parts of a washing solvent formed by combining an aqueous isopropanol containing 40 to 60 vol. percent isopropanol with a low molecular weight aliphatic OX0 organic solvent which boils in the range of 56.5 to 97 C; and dissolves less than 3 vol. percent C parafiinic oil, so that said washing solvent contains 5 to 30 vol. percent of said OX0 organic solvent.

2. A process in accordance with claim 1 wherein said OX0 organic solvent is selected from the class of C to C aliphatic ketones and esters.

3. A process in accordance with claim 1 wherein said 0x0 organic solvent is methyl ethyl ketone.

4. A process in accordance with claim 1 wherein said The attached table presents pertinent data. OX0 organic solvent is acetone.

Table 1 DATA AND INSPECTIONS 0N USE OF SELECTED SOLVENTS Selected Solvent Used 502%I tron (Con- Sec. ButylA1c... Acetone M.E.K Ethyl n.01..1

ro M1. 613 Acid Oil U ed R00 800 800-- 800 Percent Pepper Sludge, 613 Add nil 0.6% 0.6% 0.6%- 0.6% M1. IPOH sed 600 600 600 600 Ml. Selected Solvent Used r- 200 Ml. IPOH-- 200 Ml. SBOH 208 Ml. Ace- 200 Ml. MEK

one. No. of Washes Used 1 1 1 1 Vol. Percent Selected Solvent Total 800 0 25 25 25 Ml. Wash. MLOI Satd. NmCOs Used as Neutraliz- 70 70 7 70--. 70

ing Agent. Highest Neutralizing Temn C 55 C 55 C 55 C 55 C S ec. Neutral on Color, Sayb 4 n n n 2 OD Z, Clay Perc. Oil Color, Sayb lt +30 un +30 p +30 un +30 up +30 Mi Optical Density, Clay Pcrc. Oil .312 .l94 .209" .188.-. 207 2, Max, USP Garb. Subst., Perc. Oil 1.31-. 2.30-- 1.86-. 1.53.-. 1.31 3 Max.

E'IOH=Ethyl Alcohol. M.E.K.=Methyl ethyl ketone. SB 0H=Secondary butyl alcohol. IPOH =Isopr0panoL References Cited in the file of this patent UNITED STATES PATENTS 1,760,129 Fischer May 27, 1930 1,791,926 Gallagher Feb. 10, 1931 2,159,444 McCluer ct al. May 23, 1939 2,335,006 Giraitis Nov. 23, 1943 2,515,197 Cohen July 18, 1950' 2,788,310 Wilson et; al. Apr. 4, 1957' 

1. IN A A PROCESS FOR WASHING A WHITE OIL FORMED BY SULFURIC ACID TREATMENT FOLLOWING NEUTRALIZATION OF THE TREATED OIL TO REMOVE COLOR-FORMING ORGANIC IMPURITIES FROM SAID OIL, THE IMPROVEMENT WHICH COMPRISES WASHING SAID OIL WITH ABOUT EQUAL PARTS OF A WASHING SOLVENT FORMED BY COMBINING AN AQUEOUS ISOPROPANOL CONTAINING 40 TO 60 VOL. PERCENT ISOPROPANOL WITH A LOW MOLECULAR WEIGHT ALIPHATIC OXO ORGANIC SOLVENT WHICH BOILS IN THE RANGE OF 56.5 TO 97*C. AND DISSOLVES LESS THAN 3 VOL. PERCENT C20+ PARAFFINIC OIL, SO THAT SAID WASHING SOLVENT CONTAINS 5 TO 30 VOL. PERCENT OF SAID OXO ORGANIC SOLVENT. 